Ognjen Ilic, postdoctoral scholar in Professor Harry Atwater’s laboratory, and colleagues have designed a way to levitate and propel objects using only light, by creating specific nanoscale patterning on the objects' surfaces. "We have come up with a method that could levitate macroscopic objects," says Professor Atwater, who is also the director of the Joint Center for Artificial Photosynthesis. "There is an audaciously interesting application to use this technique as a means for propulsion of a new generation of spacecraft. We're a long way from actually doing that, but we are in the process of testing out the principles." [Caltech story]
Julia Greer, Professor of Materials Science, Mechanics and Medical Engineering, and colleagues have determined that the failure of architected materials—the point at which they break when compressed or stretched—can be described using classical continuum mechanics, which models the behavior of a material as a continuous mass rather than as individual (or "discrete") particles. This finding implies a duality to the nature of these materials—in that they can be thought of both as individual particles and also as a single collective. [Caltech story]
Nadia Lapusta, Professor of Mechanical Engineering and Geophysics, creates computer models of earthquakes by integrating an astonishing range of data—on scales from thousands of kilometers down to microns and from millennia down to thousandths of a second. “You have to understand the mechanics across the entire earthquake system, starting at the micrometer scale,” says Professor Lapusta. “This is the challenge.” Her numerical models rely upon field observations, seismic monitoring, lab experiments, and theoretical science, while complementing those endeavors with a new perspective. The predictions expand researchers’ view beyond the limits of direct observation—which is important for events that occur across thousands of years. [Breakthrough story] [ENGenious story]
Professor Yisong Yue is collaborating with Caltech seismologists to use artificial intelligence (AI) to improve the automated processes that identify earthquake waves and assess the strength, speed, and direction of shaking in real time. Professor Yue explains, “the reasons why AI can be a good tool have to do with scale and complexity coupled with an abundant amount of data. Earthquake monitoring systems generate massive data sets that need to be processed in order to provide useful information to scientists. AI can do that faster and more accurately than humans can, and even find patterns that would otherwise escape the human eye.” [Read the full Q&A]
"Projections with current climate models—for example, of how features such as rainfall extremes will change—still have large uncertainties, and the uncertainties are poorly quantified," says Professor Tapio Schneider, principal investigator of the Climate Modeling Alliance (CliMA). "For cities planning their stormwater management infrastructure to withstand the next 100 years' worth of floods, this is a serious issue; concrete answers about the likely range of climate outcomes are key for planning." The new climate model will be built by a consortium of researchers led by Caltech, in partnership with MIT; the Naval Postgraduate School (NPS); and JPL, which Caltech manages for NASA. It will use data-assimilation and machine-learning tools to improve itself in real time, harnessing both Earth observations and the nested high-resolution simulations. "The success of computational weather forecasting demonstrates the power of using data to improve the accuracy of computer models; we aim to bring the same successes to climate prediction," says Professor Andrew Stuart. [Caltech story]
Chiara Daraio, Professor of Mechanical Engineering and Applied Physics, and colleagues have developed phononic devices that include parts that vibrate extremely fast, moving back and forth up to tens of millions of times per second. The devices were developed by creating silicon nitride drums that are just 90 nanometers thick. The drums are arranged into grids, with different grid patterns having different properties. Professor Daraio, along with former Caltech postdoctoral scholar Jinwoong Cha, have shown that arrays of these drums can act as tunable filters for signals of different frequencies and can act like one-way valves for high-frequency waves. [Caltech story]
Thanks to Professor Pietro Perona and his graduate students including Grant Van Horn and Sara Beery, the next wildlife photo you snap might set you on a path to helping map life on Earth. “The whole web, this huge repository of wonderful information, is indexed by words,” Perona says. “But when we have an image—a visual query—we don’t know what to do unless there is an expert next to us. We’ve gotten so numb to the idea that we’ll never find the answer out.” [Breakthrough story]
Professor José Andrade’s research team including Postdoctoral researchers Ivan Vlahinic and Jason Marshall have helped the InSight Mars lander boldly go where no one has gone before: beneath the surface of Mars. InSight is equipped with two main instrument packages: a seismometer for studying how seismic waves (for example, from marsquakes and meteorite impacts) travel through the planet and a "mole" that will burrow into the ground, dragging a tether with temperature sensors behind it to measure how temperatures change with depth on the planet. These instruments will tell scientists about Mars's interior structure (similar to the way an ultrasound lets doctors "see" inside a human body) and also about the heat flow from the planet's interior. When designing the mole the engineers at JPL wanted to be certain that it would be capable of reaching the necessary depth, and so they called on Professor Andrade, an expert on the physics of granular materials. He was able to develop new computer models that helped the JPL team predict the mole's effectiveness in Martian soil. Unless the mole encounters an obstacle, Andrade is confident that it will be successful. [Caltech story]
Ten years ago, Caltech and City of Hope forged a partnership that combined what each institute was best at—engineering and medicine, respectively—with the goal of developing new biomedical technologies. At this year’s partnership celebration two projects were highlighted one involving Professor Yu-Chong Tai’s work on tracking tumors and the other building on Professor Morteza Gharib’s device to measure heart health. [Caltech story] [ENGenious MedE feature]
Andrei Faraon, Professor of Applied Physics, and colleagues have introduced a technology called "folded metasurface optics," which is a way of printing multiple types of metasurfaces onto either side of a substrate, like glass. In this way, the substrate itself becomes the propagation space for the light. As a proof of concept, the team used the technique to build a spectrometer. Such compact spectrometers have a variety of possible uses, including as a noninvasive blood-glucose measuring system. [Caltech story]
